Need A Little Help

Hey guys, this is my first time posting here (although I've been reading the forums for a while now). I'm looking for a good UNIX (or UNIX based/UNIX-like) distro to install on an old Dell Dimension 2400 Destop. I've done ALOT of research on the different distros and I've tried a few out but I was wondering which would be best for what I want to do. I want to use the machine for programming, light internet/e-mail use, and web design. A nice, clean, customizable (but semi-lightweight) desktop environment would be ideal. It's hard finding distros compatible with my machine, but here are the ones I've tried:

- FreeBsd 9.1: This was the most successful one so far. Everything went smoothly but Xorg was very bland and installing Gnome or KDE on it didn't work either. If I had to go back to this I would.

- Ubuntu 12.10: Gave me so many issues. Came to the conclusion my machine was to old to run it.